Snap action mechanism for operating electric switches



Dec. 21, 1937. T. G. RICHMOND SNAP ACTION MECHANISM FOR OPERATINGELECTRIC SWITCHES Filed Sept. 22, 1936 (j @MLAWMDZ ?$4 fa) a w PatentedDec. 21, 1937 UNITED STATES T OFFICE Thomas Guthrig Richmond, Glasgow,Scotland Application September 22, 1936, Serial No. 102,021 In GreatBritain October it, 1935 ll Claims.

This invention relates to snap action mechanism for operating electricswitches, valves, or the like, and is an improvement-in or amodification of the invention described and claimed in the specificationof my application No. 46,200

filed 22nd October, 1935.

According to the present invention, the resilient means described in theabove mentioned specification which applies the lateral pressure to theoperative member isvformed as a bimetallic element and itselfconstitutes the thermally sensitive member.

The invention also consists in a thermostat or thermostatically operatedswitch, valve or the like, as described in the above mentionedspecification, in which the spring member and its depending tongue whichmakes contact with the strut member or the operating member is made as abimetallic strip and itself forms the thermally sensitive member.

One form of the invention will now be described by way of example withreference to the accom-= panying drawing, in which:

Figure 1 is a plan of the thermally sensitive element.

Figure 2 is a sectional elevation of one form oi a thermostaticallyoperated electric switch.

Figure Sis a sectional elevation of another form of a thermostaticallyoperated electric switch.

Figure 4 is a sectional elevation of a themestatically operated gasvalve.

In carrying the invention into effect according to the form as shown inFigures 1 and 2 of the drawing as applied to, a thermostatically con;trolled switch as illustrated in Figure 1- of application No. 46,200,filed 22nd October, 1935, the spring member and its depending tongue M,which presses against the strut member I8 is made of two metals joinedtogether in any known manner so as to form a bimetallic thermallysensitive member. The two metals of the bimetallic member 20 are soarranged that on heating up additional pressure is applied laterally tothe strut member l8 so as to cause the contacts I and" 8 to snap apart.Arrangements may be made to heat the bimetallic member by passingcurrent directly through it, or it can be arranged to be heated by theair in a room or the like. Or again, a separate heating element or thelike may be situated close to or around the thermally sensitive memberto heat it for controlling the contacts on the operating member.

According to the form shown in Figure 3, as applied to the form shown inFigure 3 of applica- 56 tion No. 46,200 filed 22nd October, 1935, thebi- (Ql. faw -13$) metallic member 20 is made to press upon the strutmember .l near the bracket 3, which gives a very simple and effectiveconstruction.

An arrangement is shown in Figure 4 of the in vention applied to a gasvalve, as shown in Figure 10 of application No. 46,200, filed 22ndOctober, 1935, in which the tongue 2| presses on the operating member 5on which the valve Ed is mounted which closes the opening 53.-

The adjusting screw 28 with its handle 3lis provided and is screwed intothe yoke 2? or other suitable means fixed to the base i of the device inall the modifications shown.

If desired, the bimetallic member 2d may be made to decrease itspressure when heated so that the operating member may be moved to closethe contacts.

The switch made according to the present invention can be used as athermostat or as a delay action switchv mechanism for working otherdevices, such as trafiic signals, overloads, safety switches or thelike, the current passing through the thermally sensitive member orthrough the separate heater, as desired. In a delay action switch thetime it takes to heat up the bimetallic element to operate the switch isso adjusted as to give the required delay in the action.

Additional contacts may be made below the usual contacts in place of thestop it which limits the travel of the operating member. If desired, thebimetallic thermally sensitive member may be applied to the type ofswitch which does not automatically return to its original position butwhen operated by the thermally sensitive member remains in the trippedposition, as shown in Figure 9 of the specification of our applicationNo. 6,200, filed 22nd October, 1935, and has to be reset by other means.

It is to be understood that arrangements of parts and construction ofdetails may be made other than those described according to requirementswithout departing from the scope of the invention.

I claim:

1. A snap action make and break mechanism comprising in combination abody, an operating member pivoted at one end to said body, a memher atthe other end of said body, with which the other end of said operatingmember makes contact, a member pivotally supported at one end on saidbody and at the other end on said operating member applying a resilientturning moment to said operating member in one direction, and aresilient bimetallic member mounted upon said body adapted to apply aforce which creates a turning moment which is applied in the oppositedirection to said operating member, movement of said operating membertaking place when one turning moment overbalances the otherturningmoment, and the snap action being due to the overbalanced turning momentdecreasing more rapidly than the other turning moment and taking placebefore the said operating member reaches the dead centre or neutralposition.

2; A snap action make and break short gap mechanism, comprising incombination, a body, two upstanding supports on said body, an operatingmember pivotally supported at one end on one of said supports, afloating member pivotally supported upon said operating member and saidother support applying a resilient turning moment in one direction, amember on said body, a member on said operating member contacting withsaid body member, and a resilient bimetallic member mounted upon saidbody adapted to apply a force which creates a turning moment which isapplied in the opposite direction to said operating member, said snapaction taking place before the said operating member reaches the deadcentre or neutral position.

3. A snap action make and break mechanism comprising in combination abody, a non-resilient operating member pivoted at one end to said body,a member at the other end of said body, with which the other end of saidoperating member makes contact, a member pivotally supported at one endon said body and at the other end on said operating member applying aresilient turning moment to said operating member in one direction, abimetallic member for applying a re-= silient force to said operatingmember to create a turning moment in the opposite direction, movement ofsaid operating member taking place when one turning moment overbalancesthe other turning moment, the snap action being due tothe overbalancedturning moment decreasing more rapidly than the other turning moment,and means to prevent said operating member passing through the deadcentre or neutral position.

4. A snap action make and break short gap,

. through dead centre or neutral position when the contacting membersare opened and a resilient bimetallic member mounted upon said body andpressing upon said operating member applying a turning moment in theopposite direction.

5. A snap action make andbreak short gap thermostatic switch, comprisingin combination, a body, two upstanding supports on said body, anon-resilient operating member pivotally supported at one end on one ofsaid supports, a floating member pivotally supported upon said operatingmember and said other support applying a resilient turning moment in onedirection, a contact on said body, a contact on said operating memberengaging with said body contact, means for preventing said operatingmember passing through dead centre or neutral position when the contactsare opened and a resilient bimetallic member mounted upon said body andpressing,

aioaiei upon said floating member applying a turning moment in theopposite direction.

6. A snap action make and break short gap thermostatic switch comprisingin combination, a body, two upstanding supports on said body, anon-resilient operating member pivotally supported at one end on one ofsaid supports, a floating member pivotally supported upon said operatingmember and said other support applying a resilient turning moment in onedirection, a contact on said body, a contact on said operating memberengaging with said body contact, means for preventing said operatingmember passing through dead centre or neutral position when the contactsare opened and a resilient bimetallic member mounted upon said body .andpressing upon said operating member applying a turning moment in theopposite direction.

7. A snap action make and break short gap switch comprising incombination a body, two upstanding supports on said body, anon-resilient operating member pivotally supported at one end on one oisaid supports, a floating member pivotally supported upon said operatingmember and said other support applying a resilient turning moment in onedirection to said operating member, means for -'adjusting the endpressure on said floating member, a contact on said body, a contact onsaid operating member engaging with said body contact, means forpreventing said!- operating member passing through dead centre orneutral position when the contacts are openedv and a resilientbimetallic member gmounted upon said body and pressing upon saidoperating mem= ber applying a turning moment in the opposite direction.

8. A snap action make and break short gap thermostatic switch comprisingin combination, a body, two upstanding supports on said body, anon-resilient operating member pivotally supported at one end on one ofsaid supports, a floating member pivotally supported upon said operatingmember and said other support applying a resilient turning moment in onedirection, a contact on said body, a contact on said operating memberengaging with said body contact, means for preventing said operatingmember passing through dead centre or neutral position when the contactsare opened and a resilient bimetallic member mounted upon said body andpressing upon said floating member applying a turning moment in theopposite direction.

9. A snap action make and break short gap switch comprisingincombination, a body, two upstandingsupports on said body, anon-resilient operating member pivotally supported at one end on one ofsaid supports, a floating member pivotally supported upon said operatingmember and said other support applying a resilient turning moment in onedirection, means for adjusting the end pressure on said floating member,a contact on said body, a contact on said operating member engaging withsaid body a knife edge on said operating member enga ing said V grooveon said support, a cnp shapetl bearing on said operating member, afloating member supported in said cup hearings on the support andoperating member respectively, saiti floating member applying aresilient turning moment in one direction to said operating mem ber,means for adjusting the force exerted by said floating member upon saidoperating memher, a contact on a portion of said operating member remotefrom the two bearings, a COX1- tact on said body adapted to be engagedby said contact on said operating member, a stop to iimit the gapbetween the contacts and to pre= vent the operating member from passingthrough dead centre or; neutral position, and a resilient bimetallicmember mounted upon said body to press upon said operating member forapplying a turning moment in the opposite direction.

11. A snap action make and break short gap switch comprising incombination, a body, two upstanding supports on said body, a v groove inone support, ciip=sheped bearing in the other support, non-reariiicntoperating member, a knife edge on said operating member engaging said Vgroove on said support, a cup=sirianed bearing on said operating member,a floating member supported in said cup hearings on the support andoperating member respective- 1y, said floating m mber appiying aresilient turningrnoment in one direction to said operating member,means for aciinsting' the iorce errerteol by said floating member n saidoperat-' ing member, a contact on a poi, on oi said operating memberremote from the two hearings, a contact on said body adapted. to heengaged by said, contact on operating m mber, a stop to limit the gapetween the contacts and to prevent the operating member from passingthrough deed centre or nentrai position and a resilient bimetallicmember mounted upon said body to press upon said floating member forapplying a 0 turning moment in the opposite direction.

THUMAS GUTHRIG RiGi-iiimND.

